Mohammad Alizadeh

Millions of little minions: using packets for low latency network programming and visibility

By: 
Vimalkumar Jeyakumar, Mohammad Alizadeh, Yilong Geng, Changhoon Kim, David Mazières
Appears in: 
CCR August 2014

This paper presents a practical approach to rapidly introducing new dataplane functionality into networks: End-hosts embed tiny programs into packets to actively query and manipulate a network’s internal state. We show how this “tiny packet program” (TPP) interface gives end-hosts unprecedented visibility into network behavior, enabling them to work with the network to achieve a desired functionality.

CONGA: distributed congestion-aware load balancing for datacenters

By: 
Mohammad Alizadeh, Tom Edsall, Sarang Dharmapurikar, Ramanan Vaidyanathan, Kevin Chu, Andy Fingerhut, Vinh The Lam, Francis Matus, Rong Pan, Navindra Yadav, George Varghese
Appears in: 
CCR August 2014

We present the design, implementation, and evaluation of CONGA, a network-based distributed congestion-aware load balancing mechanism for datacenters. CONGA exploits recent trends including the use of regular Clos topologies and overlays for network virtualization. It splits TCP flows into flowlets, estimates real-time congestion on fabric paths, and allocates flowlets to paths based on feedback from remote switches. This enables CONGA to efficiently balance load and seamlessly handle asymmetry, without requiring any TCP modifications.

Data Center TCP (DCTCP)

By: 
Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye, Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan
Appears in: 
CCR October 2010

Cloud data centers host diverse applications, mixing workloads that require small predictable latency with others requiring large sustained throughput. In this environment, today’s state-of-the-art TCP protocol falls short. We present measurements of a 6000 server production cluster and reveal impairments that lead to high application latencies, rooted in TCP’s demands on the limited buffer space available in data center switches. For example, bandwidth hungry “background” flows build up queues at the switches, and thus impact the performance of latency sensitive “foreground” traffic.

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